At approximately 1:15 p.m. on Feb. 1, a man later identified as Ecevit Sanli, 40, stopped outside a personnel entrance of the U.S. embassy in Ankara and detonated a belt carrying 13 lb. (6 kg) of explosives, as well as a hand grenade, killing one Turkish security guard, wounding several others and blowing himself in pieces.

Amid the confusion that reigned over the ensuing few hours, Turkish news and social-media sites buzzed with the names of possible culprits. By late afternoon, the list that emerged began to read like a register of every conflict in which Turkey — NATO member, E.U. hopeful and rising regional power — has played a part over the past decade.

First came the usual suspects. There was al-Qaeda, which has already been blamed for a series of deadly terrorist attacks in Istanbul in 2003. Then came the Kurdistan Workers’ Party, which has waged war against Turkey for almost three decades and whose imprisoned leader recently agreed to talks with the government. Then there was Syria, which has turned from best friend to ultimate foe since the beginning of the armed insurgency to unseat President Bashar Assad and which has been suspected, at least by the Turks, of having a hand in a deadly bombing in Gaziantep, a Turkish city, in August. There was Iran, which has warned Turkey that its belligerence toward Assad — and particularly the recent deployment of NATO Patriot missile batteries along the country’s border with Syria — may soon usher in another world war. The list closed with ultra-nationalists, rogue intelligence operatives and homegrown Islamic extremists.

By the end of the day, however, it had become clear that the group that appeared most likely to have been behind Friday’s bombing was a Marxist organization: the Revolutionary People’s Liberation Party-Front (DHKP-C). High-ranking Turkish officials, including Prime Minister Recep Tayyip Erdogan, declared that Sanli, the suicide bomber, was a member of the group. He had been incarcerated between 1997 and 2002 on terrorism charges.

In a lengthy, rambling statement posted online on Saturday, the DHKP-C claimed responsibility for the embassy attack, called the U.S. “the murderer of the people of the world” and warned the Obama Administration to “get your bases, your missiles and your Patriots the hell out of our country.” It added: “It is the Syrian people who will decide how, and by whom, Syria will be governed. The AKP government is a lackey to imperialists who seek to overthrow al-Assad, who refuses to bow his neck to them … We condemn the use our land for the imperialists’ interests against Syria.”

The Patriots referred to by the statement are the interceptor missiles deployed recently along Turkey’s border with Syria. A total of six batteries — two each sent by Germany, the Netherlands and the U.S. — have been stationed in Turkey to protect against a possible Syrian missile attack.

But did Syria put the DHKP-C up to bombing? Or was the group acting on its own? The bombing also comes on the heels of a massive police crackdown against the DHKP-C. Since the beginning of January, 85 of the group’s members have been detained. Just over a week ago, 55 of them were charged with membership in a terrorist organization. According to police sources quoted by Turkish newspapers, the group had been planning to assassinate state officials and attack foreign embassies. Friday’s suicide bombing, observers point out, came amid an uptick in DHKP-C violence. Over the past two years, the group has attacked a number of police targets, particularly in Istanbul. Last Sept. 11, in an attack that bore many similarities to the one carried out on Friday, a DHKP-C suicide bomber detonated himself inside a police station in Istanbul, killing one police officer.

That the group should decide to step up its violent campaign just as tensions between Turkey and Syria begin to reach new heights is no coincidence, says Nihat Ali Ozcan, a Turkish terrorism expert and retired army officer. During the Cold War, he says, “Syria provided a lot of facilities to this group, including camps, ammunition, etc. They had a really close relationship with Syrian intelligence.” Now that Syria and Turkey are engaged in what Ozcan calls a “war by proxy,” the DHKP-C has again reared its head. “Their activity is increasing because of the Syrian crisis.”

Henri Barkey, a former State Department official who teaches at Lehigh University, acknowledges that the group might be sympathetic to Assad but sees no direct Syrian involvement in the attack. “I don’t believe that the Syrians could get these guys to do something for them. These guys will do things because they want to. They’re like a cult. If one of the leaders decides they should go on hunger strike, they go on hunger strike and they die.” (This is precisely what happened in 2000, when 60 DHKP-C inmates died during a protest against prison conditions.) Besides, says Barkey, “the Syrians would not want something like this.” To launch such a small-scale, symbolic attack against an American embassy, given the stakes involved, he believes, makes no sense. “Just for that you’re going to risk the wrath of America? Uh-uh.”

Barkey, who spoke to TIME before the DHKP-C released its statement, predicted that the group would say it was provoked by the deployment of the interceptor missiles. “They will link it to the Patriots,” he says, “because that’s the way to justify something stupid like this. They want to look like they’re heroes, standing up and resisting.”

The DHKP-C, which has its roots in a number of radical leftist organizations that date back to the 1970s, has a markedly anti-Western agenda and makes a point of accusing successive Turkish governments of being American and NATO stooges. It has also been designated a terrorist group by the U.S., the E.U. and Turkey. Together with one of its predecessors, the Dev Sol, or Revolutionary Left, the DHKP-C is believed to be responsible for killing two retired generals, a former government minister and a top Turkish businessman. In the spring of 1991 — to protest the American role in the Gulf War — the group allegedly killed two U.S. military contractors and wounded an Air Force officer. In subsequent years, it would attempt to launch rocket attacks against a U.S. air base in southern Turkey and the American consulate in Istanbul. The continued threat, says Barkey, was one of the reasons why the consulate eventually moved to another part of the city.